Area Forecast Discussion
Issued by NWS Charleston, SC
FXUS62 KCHS 261949
Area Forecast Discussion
National Weather Service Charleston SC
349 PM EDT TUE JUL 26 2016
Atlantic high pressure will prevail through much of the week while
a weak trough persists inland.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Strong and persistent deep layered ridging is persisting across
the forecast area. The combination of warm mid level temperatures,
extensive dry air, and subsidence aloft are limiting convective
development across most of the forecast area. Some low level
moisture is advecting into our GA counties this afternoon. Radar
shows scattered showers in this area. A few thunderstorms are
possible into this evening, but they aren`t expected to be too
strong or long-lived. Plus, instability is not impressive (SBCAPEs
are barely reaching 2,500 J/kg in some locations)..
Convection will decrease this evening and skies will be mainly
clear, except for some late night showers off the coast. Lows will
be in the mid to upper 70s.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A deep layer ridge will remain centered just offshore, with low
level south-southwest winds through Thursday...becoming onshore each
afternoon near the coast. All models showing very low chances for
afternoon convection, mainly due to warm mid levels and only
marginal deep layer moisture. By Friday, upper heights begin to fall
some as a broad trough moves into the Ohio River Valley. Marginal
deep layer moisture will increase gradually by late day from
northwest to southeast, but may be too low for most of the day to
include any pop mention. Have maintained pops just below 15%, but
may need to add isolated pops if increasing moisture trends
Unfortunately, no change with the temperatures as they remain well
above normal in the mid to upper 90s for highs, and mid to upper
70s for lows. The surface dewpoint temperatures will likely mix down
into the upper 60s to around 70s each afternoon away from the coast,
which is expected to keep heat indices below any advisory levels.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Ridging overhead will weaken heading into the weekend and POPs will
return closer to climo levels with a warm and humid airmass in place
at the surface. The ridge will slide off the Southeast Coast Sunday
and modest height falls aloft will bring more unsettled weather
early next week. A cold front associated with low pressure lifting
across the Great Lakes may reach as far south as the Carolinas
before dissipating Monday and Tuesday. Global models currently focus
moisture pooling and enhanced convective initiation near this front
across North Carolina and the South Carolina Upstate Monday and
Tuesday, and with 700mb steering flow gradually shifting more WNW,
some of this activity could advect into our area during this time.
POPs well into the chance range have been introduced for the early
part of next workweek, especially across and north of the Charleston
Temps will remain well above normal through the period as the warm
and humid airmass remains anchored over the area with ample sunshine
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
VFR through 18Z Wednesday.
Extended Aviation Outlook: VFR will prevail both sites through
the rest of the work week. Very low chances for brief flight
restrictions during the afternoon with isolated
showers/thunderstorms. Better moisture along with a broad upper
trough to the north by late week and into the weekend will likely
translate to higher chances for afternoon thunderstorms.
The synoptic pattern will allow SW winds near 15 kt through
tonight. Seas will be 2-3 ft. Showers and thunderstorms are
possible, mainly seaward from the pilot buoys late tonight.
Wednesday through Sunday: No highlights expected through the
period. Atlantic high pressure will continue through the period
with south-southwest winds through the weekend. There could be
brief surges in the wind to 15 knots or so each evening and early
morning. Otherwise, winds are expected to be 15 knots or less and
seas generally 3 to 4 feet or less. Isolated to scattered mainly
late night through morning showers and thunderstorms.